Study Shows Penguins Endangered By Waning Antarctic Ice

You're listening to WEEKEND EDITION from NPR News. A study published in the journal "Nature Climate Change" says, the population of Emperor penguins in Antarctica is in danger. Hal Caswell is a scientist emeritus at the Woods Hole Oceanographic Institution. He co-authored the report. And he joins us from Amsterdam. Welcome.

HAL CASWELL: Thank you.

WERTHEIMER: You've been studying the Emperor penguin population in Antarctica. What's happening to them?

CASWELL: The Emperor penguin is affected by changes in the sea ice conditions. The projection is that all of the colonies - there are 45 of them known around the circumference of Antarctica. All 45 of them, by the end of the century, are going to be declining quite rapidly.

WERTHEIMER: We've all seen the wonderful pictures of the penguins sliding across the ice and diving into the water. Could you explain how the ice works for these creatures, and why climate change might affect them?

CASWELL: Yes. So this species breeds in colonies on sea ice. They make this long march from the edge of the ocean to breed in the middle of the winter. So if there's too much sea ice, that trudge to bring food to the chicks gets longer and more energetically expensive for the penguins, and this cuts down on their breeding success. On the other hand, if there's too little sea ice, then the basis of the Antarctic food web is not as productive.

WERTHEIMER: And it's your anticipation that the climate will change in such a way that the sea ice will shrink?

CASWELL: Yes.

WERTHEIMER: The Emperor penguin is actually on the list to be considered for protection under the U.S. Endangered Species Act. Would protected status help them?

CASWELL: Listing them as an endangered species would have several really positive effects. The biggest one is that it would provide more impetus to take action on reducing greenhouse gas emissions and slowing or halting climate change.

WERTHEIMER: You mean the penguin might become a sort of poster child for correcting the direction in which the climate is going?

CASWELL: Yes. And identifying threats to charismatic species, like the Emperor penguin, like the polar bear, is not going to be enough. But documenting threats to species like this, along with the many other impacts of climate change, is an important contribution. And it's really something that the Endangered Species Act is quite appropriate for.

WERTHEIMER: Hal Caswell is a professor at the University of Amsterdam. Thank you very much.